This section provides background information related to the present disclosure which is not necessarily prior art.
A power electronic module has been used in a vehicle to drive the vehicle with electric power. Generally, a conventional power electronic module may have a plurality of power devices and a cooler having a coolant passage to cool the power devices. Each of the power devices may have a switching element, such as an IGBT, a MOSFET, and so forth. The switching elements may cooperate together to generate the electric power for driving the vehicle. On the other hand, each of the switching elements may generate heat as well. The cooler may cool the switching elements and maintain a low temperature of switching elements so that the coolant passage may exchange heat with the switching elements.
One of the conventional power electronic modules may have a plurality of pairs of the power devices. Each pair of the power devices may be disposed along a flow direction of the coolant passage. In that case, coolant which flows through the coolant passage may exchange heat with one of the two power devices at first. Then, the warmed coolant may exchange heat with the other of the two power devices. Thus, temperature imbalance between the two power devices, which exchange heat with the same coolant passage, may occur. In other words, the power device, which is arranged on a downstream side of the coolant passage, may operate at a higher temperature than the power device, which is arranged on an upstream side of the coolant passage.
As a result, the temperature imbalance may cause resistance imbalance and circuit imbalance between the two power devices when the two power devices are used in parallel. Eventually, the temperature imbalance may influence inefficient operation of the power devices as a whole.